Rotary cutter tool

ABSTRACT

A tool assembly for boring, turning, countersinking, chamfering and facing workpiece comprising a generally cylindrical tool body with an axially extending tool slot for removably receiving a flat cutting blade. A tool driver connected to the tool body maintains rotational motion between the tool body and the workpiece. The tool body has a means for limiting depth of cut by the blade and a means for guiding the cutting blade. A blade holder in the tool body is normally retracted by a spring means so that the blade is sheathed in the body. The blade holder may be axially advanced in the tool body by relative axial movement of the tool driver and the tool body to project the cutting edge of the cutting blade, while the tool body is engaged with the workpiece for guiding the cutting blade.

United States Patent Zukas 1 Feb. 29, 1972 [54] ROTARY CUTTER TOOL 3,451,294 6/1969 Harman ..77/58 1.

[72] Inventor: Michael F. Zukas, Bayberry Road, Primary Examiner Gerald A Dost Southhold 1 1971 Attorney-Edward H. Loveman [22] Filed: June 11, 1970 57 AB RACT 21 App1.No.: 45,321 1 ST A tool assembly for boring, turning, countersinking, chamfering and facing workpiece comprising a generally cylindrical [52] 4 55:2353: tool body with an axially extending tool slot for removably [51] i a: 6 192 193 receiving a flat cutting blade. A tool driver connected to the [58] 0 are tool body maintains rotational motion between the tool body and the workpiece. The tool body has a means for limiting depth of cut by the blade and a means for guiding the cutting [56] References Cited blade. A blade holder in the tool body is normally retracted by UNITED STATES PATENTS a spring means so that the blade is sheathed in the body. The

blade holder may be ax1ally advanced 1n the tool body by rela- 2l4,720 4/1879 Shur ..77/58 M five axial movement f the loo} driver and the too] body to 2,398,362 4/1946. Dare 77/58 L project the cutting edge of the cutting blade, while the tool 2,401,074 5/ 1946 Huelster. ....77 M body is engaged with the workpiece for guiding the cutting 2,495,583 1/1950 Heron ....77/58 M b1ade 2,545,443 3/1951 Bowren ..77/58 L' 2,984,] 30 5/1961 11 Claims, 17 Drawing Figures Lentz ..77/58 A PAIENTEDreazs I972 3,645,640

sum 1 0F 8 FIG.!

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MICHAEL F. ZUKAS mm mt v5 ATTORNEY ROTARY CU'I'IER TOOL This invention relates to a rotary tool having a replaceable cutting blade and more particularly relates to a rotary tool assembly having replaceable cutting blade and a guide which guides the blade in cutting the workpiece.

A principal difficulty encountered with conventional rotary cutting tools used in drill presses, lathes, milling machines and the like, is the necessity to provide some apparatus external of the tool for controlling depth of cut, rate of tool feed or advance, tool guidance, etc. This apparatus, of course, increases the cost and complexity of such machines. When conventional cutting tools are employed in hand held electric-powered or hand-powered drills, routers, chamfering devices, hole facers, shaft dressers, and the like, the absence of effective tool guidance and means for controlling depth of cut becomes particularly troublesome. Another difficulty encountered with conventional rotary tools is the tendency of fixed blades to bind when performing drilling, boring, facing, dressing, chamfering, beveling, routing and similar operations.

The present invention is directed at overcoming the above and other difficulties and disadvantages of prior rotary tools by providing a tool assembly or tool structure adapted for use in a holder and wherein there is relative rotary motion between a cutting blade and the work piece to which the cutting blade is applied.

According to the invention a tool is provided in which there is integral guidance and control means for the cutting blade. There is provided means forming part of the tool holder for controlling depth of cut by the cutting blade and for controlling feed rate or tool advance per revolution of relative rotation between the workpiece and tool. Further in accordance with the invention, the structure of the tool holder is arranged to support the cutting blade in such manner with respect to tool guidance means, that the rigidity needed for the cutting operation is inherent in the tool, and the rigidity external to the tool as to the workpiece mounting or the support for the rotary tool is of no material consequence.

The invention further involves a tool having a replaceable cutting blade which is movable relative to its body, although in some embodiments the cutting blade may be fixed in one position. In any case, the depth of cut by the cutting blade is controlled by projecting the cutting blade a predetermined, set distance from its holder. The holder limits the depth of cut by the cutting blade and determines the rate of feed or advance per revolution of relative rotation between the workpiece and tool. By this arrangement, the torque required for tool operation is constant and not varying or variable as occurs in uncontrolled cutting means.

In operation of a tool assembly having a movable cutting blade, the means for limiting the depth of cut contacts the workpiece first, and then the'cutting blade is made to extend and engage in the cutting operation while the tool is rotating. Additionally, the cutting blade may be disengaged from the workpiece by retracting the blade within its holder while the tool body remains in rotational contact with the workpiece. This operation facilitates cutting of thin materials, and also prevents or relieves binding in thick materials. Such materials can be metal, wood, plastic and other cuttable materials.

The tool assembly having a fixed cutting blade is arranged so that the cutting blade contacts the workpiece before the blade holder which includes a depth of cut limiting means. The cutting blade in this embodiment is fixed in position with respect to its holder and projects a fixed distance from its holder.

Accordingly, it is a principal object of the present invention to provide a tool assembly having an integral guide means for a cutting blade.

Another object of the instant invention is to provide a tool assembly having integral means for controlling depth of cut and rate of cutting blade advance per revolution of the tool or workpiece.

Still another object of the instant invention is to provide a tool assembly having means for facilitating replaceability and interchangeability of cutting blades.

Another-object of the instant invention is to provide a tool means having a cutting blade supported in a movable holder.

A further object of the instant invention is to provide a tool assembly having a tool body with a cutting blade wherein the cutting blade extends to engage a workpiece during the cutting operation and is retracted to disengage from the workpiece while the tool body remains in contact with the workpiece.

These and other objects and many of the attendant advantages of this invention will readily be appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

FIG. 1 is a side elevational view partially in section of a boring or hole enlarging tool assembly embodying a first form of the invention.

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1.

FIG. 3 is an exploded perspective view of parts of the tool assembly of FIGS. 1 and 2.

FIG. 4 is a side elevational view of another boring or hole enlarging tool embodying a second form of the invention.

FIG. 5 is another side elevational view taken from the view of P16. 4 along line 5-5 of FIG. 4.

FIG. 6 is a cross-sectional view taken along line 6-6 of FIG. 4.

FIG. 7 is a longitudinal sectional view taken along line 77 of FIG. 5.

FIG. 8 is an exploded perspective view of parts of the tool assembly of FIGS. 4-7.

FIG. 9 is a longitudinal sectional view of a countersinking or internal chamfering tool assembly embodying a third form of the invention.

FIG. 10 is a cross-sectional view taken along line 10-10 of FIG. 9.

FIG. 11 is an exploded perspective view on a reduced scale of parts of the tool assembly of FIGS. 9 and 10.

FIG. 12 is a longitudinal sectional view of an external chamfering tool assembly embodying a fourth form of the invention.

FIG. 13 is an exploded perspective view of parts of the tool assembly of FIG. 12.

FIG. 14 is a longitudinal sectional view of an inside diameter boring, hole facing, forming and counterboring tool assembly embodying a fifth form of the invention.

FIG. 15 is an exploded perspective view of parts of the tool assembly of FIG. 14.

FIG. 16 is a longitudinal sectional view of the outside diameter cutting tool assembly embodying a sixth form of the invention.

FIG. 17 is an exploded perspective view of parts of the tool assembly of FIG. 16.

Referring now to the drawings wherein like reference numerals designate like or corresponding parts throughout the figures thereof, there is shown in FIGS. 1, 2 and 3, a tool assembly generally designated by the reference symbol T1 comprising a generally conical, tapered tool body 20. This body is formed with a multiplicity of annular steps 22 defining cylindrical sections 23 having successively smaller diameters from the widest end to the narrowest end of the body. A flat chordal face 24 (FIGS. 2 and 3) is formed on the body 20 for its entire length. A radial slot 26 is formed in the body. This slot extends between the cylindrical section 23 and a central axis 29 of the body. A cap 30 is provided for the body. This cap has a circular face 32, a cylindrical flange 34 and an axial nipple 35. The diameter of face 32 is substantially equal to the widest end of body 20 to fit thereon. Body 20 abuts a ledge 33 in cap 30. Screws or bolts 36 extend through holes 38 in the cap and engage in threaded holes 40 in the body 20 to thus secure the cap 30 to the body 20. A driver member 44 is provided for the body 20. This member has a cylindrical shaft 46 which extends axially through the nipple 35 which is integrally formed with the cap 30. An annular flange 45 integrally formed on the inner end of the shaft 46 is located between the circular face 32 of the cap 30 and an end face 47 of the body 20. The shanks of screws 36 extend through holes 49 in the flange 45. External threads 50 are formed on shaft 46 and are located so as to extend outwardly beyond nipple 35. An internally threaded collar 51 may be adjustably positioned on the shaft 46 and locked in place by a setscrew 52 engaged in a radial threaded hole 53- in the collar 51. The position of the collar 51 determines the depth of cut of the-cutting blade and thereby the rate of feed, i.e., cutting blade advance per revolution.

A cylindrical recess 56 is provided in the wider end of body 20. This recess is coaxial with the axis of body 20. in this recess is disposed a cylindrical blade holder 60 which is movable axially a distance determined by the position of driver 44 with respect to body 20. Axially extending blind holes 58 in 'blade holder 60 house coil springs 62 which bear against an inner circular face 64 of recess 56 to bias the blade holder 60 against the flat circular inner face of the flange 45. g

In the embodiment of FIG. 1 a flat tapered cutting blade 70 fits slidably in slot 26 and is secured in a radial slot 72 formed in the cylindrical holder 60 by a pair of setscrews 74 which engage threaded holes 75 in the blade holder 60. The blade 70 has a plurality of steps 76 formed in its outer edge 78 with edges '79 of these steps normally registering with or behind the annular steps 22in the body 20 when the blade holder is retracted by the expanded springs 62. Access holes 80 are formed in the wider portions of body 20 and open into recess 56 to provide access to screws 74 for disengagement of blade 70 and for reengagement therewith. Radial threaded holes 82 which open into slot 26 are also provided in body 20 to receive screws 84 which are in contact with the straight back edge 85 of the blade 70. These screws serve as guides and a radial adjustment means for the movable blade 70.

In operation of the tool assembly T1, the tool body 20 is inserted into a previously drilled hole in a workpiece until one of 35 the cylindrical sections 23 having'a diameter slightly less then the hole in the workpiece fits into the hole. The step 22 at the end of this cylindrical section 23 bears on the surface of the workpiece at the outer end of the hole. The cylindrical sections 23 thus serve as guidance means for the tool body and cutting blade, and provides stability for positioning of the tool assembly with respect to the work piece. The cutting blade 70, which is movable axially, is set for extension of cutting edges 79 by the positioning of collar 51 on shaft 46. The shoulders or annular steps 22 serve as depth of cut limiting means for the tool assembly. Advance of the blade with respect to the hole being dressed or enlarged in the workpiece is determined by the extent to which the cutting edge 79 of the cutting blade projects from the step 22 of the tool body and by the steps or shoulders 22 themselves. As torque is applied to the shaft 46 of the tool driver member 44, the torque force is transmitted via the screws 36 to the tool body 20 which in turn drives the cutting blade 70. The cutting edges 79 of the blade are extended when axial pressure is applied between the tool assembly and workpiece. While cutting the workpiece, the blade is rigidly supported and well able to dissipate heat generated during the cutting operation. An electric hand-held drill, hand brace or other driving means may be used with shaft 46 for driving the tool assembly. Alternatively the shaft 46 may be held stationary and the workpiece rotated as in a lathe or the like. In any case, the driver 44 will advance tool holder 60, compress springs 62, and project the cutting blade from its sheath in body 20. The blade will be projected a distance equal to that set by the position of the collar 51 on the shaft 46. As one hole diameter is completed in the workpiece the fully inserted section 23 will guide the tool assembly axially for the next larger hole diameter. The hole in the workpiece thus serves as a guide means for cutting the next larger hole diameter. At any time when there is relative rotational motion between the workpiece and the tool assembly, the cutting operation may be stopped by merely retracting the driver 44. This allows the springs 62 to expand and retract the blade holder 60 along with cutting blade 70 which fully retracts into the sheathing slot 26 of the body 20.

FIGS. 4-8 show a second tool assembly generally designated as symbol T2, which has certain parts corresponding to those of tool assembly T1 and which are therefore identically numbered. Tool assembly T2 like tool assembly Tl may be used to generate a single diameter hole or several hole diameters in succession. Tool assembly T2 has a generally conical, tapered tool body 20a having cylindrical sections 23 of progressively increasing diameters from the narrowest end to the widest end of the tool body 200. An annular stepor shoulder 22 is provided between each of the cylindrical sections 23. A driving shaft 46a is integral with the tool body 200 and extends axially thereof. A radial slot 26 in the tool body 20a is adapted to receive stepped cutting blade a. A setscrew 90 set in an axially extending hole 92 bears against the back end 93 of the blade 70a and sets the cutting blade for depth of cut by determining the distance by which cutting edges 79 extend beyond the shoulders 22. The radial position of the blade 70a in slot 26 is determined by setscrews 84 inserted in threaded radial holes 82 communicating with the slot 26. A pair of setscrews 94 are inserted in threaded radially spaced holes 96 and bear against the blade 70a to secure the blade in the slot 26.

In operation of the tool assembly, the cutting blade 70a contacts the workpiece before the shoulder 22 which limits the depth of cut. This contrasts with the operation of the tool assembly Tl where the shoulders of the tool body will contact the workpiece before the blade is extended by the axial force applied between the workpiece and the driving member 44. Cutting of the hole diameter in the workpiece will proceed until the next step of the cutting blade reaches the workpiece. Then thehole itself will serve as a guide for the forming of the next hole diameter while the next previous cylindrical section 23 rotates in the hole just formed.

FIGS. 9, 1 0 and 11 show a tool assembly generally designated by symbol T3 which may be used to bore the inside face of a hole, to counterbore holes and/or to bevel or finish the ends of holes. The tool includes guidance and depth of out control means as will now be explained. Parts corresponding to those of the tool assemblies T1 and T2 areidentically numbered.

Cylindrical tool body 20b has a cylindrical bore or recess 56b in which is fitted the cylindrical holder 60 for the cutting blade 70b. The tool body has a conical nose guide or tip 100 and a cylindrical guide face 102 with a shoulder 104. A cylindrical shaft 46b of a driver member 44b extends axially through an apertured end, flanged end 32b of cap 30b which mounts concentrically on the tool body 20b and is held in place by a cap retaining screw 106. This screw is threaded in hole 108 in the cylindrical cap 30b to engage the tool body 20b. A collar 51 adjustably engages a thread 50 of a shaft 46b and is held in place by a locking screw 53. The driving member 44b has a cylindrical end portion 45b provided with a diametral bore 112 which receives a pin 114. This pin extends outwardly on opposite sides of the driver end portion 45b and slidably engages in notches 116 formed in the tool body 20 b. The inner circular end face 118 of the driver member 44 contacts an end face of the blade holder 60. The blade holder 60 is retracted against the driver member 44b by the coil springs 62 set in holes 58. Screws 74 in holes retain the blade 70b in the blade holder 70b and may be reached through holes b in tool body 20b for disengaging the blade 70b. A slot 26b is formed in the tool body 20b to slidably receive the blade 70b. The inclined cutting edge 79b of the blade normally registers with the edge 120 of the slot 26b in a conical nose or tip of the tool body 20b. The blade is held retracted along with blade holder 60 by the expanded springs 62. The cutting blade is movable axially of the assembly by advancing the driver member 44b which advances the tool holder and cutting blade. This extends the cutting edge 79b from the conical nose or tip 100 for cutting the workpiece.

in operation of tool assembly T3, the guide piece 100 is engaged in a hole of a workpiece and in contact with the edges therewith. During relative rotational motion of the workpiece and tool body the driver 44b is axially advanced such that the springs 62 are compressed and the cutting edge of the blade is projected beyond the tip 100. The blade 70b moves axially to engage and cut the workpiece. The extent of movement of blade 70b is determined by the position of the collar 51. When the driver 44b is slightly retracted, cutting ceases since the blade is automatically retracted inside the tool body and is sheathed in the slot 26b. Relative rotational motion between the tool body and workpiece may continue during this retraction movement of the cutting blade.

It is possible to arrange the tool assembly T3 in a manner analogous to that shown in connection with the tool assembly T2, by merely removably mounting the blade 70b in the tool body. The tool will be radially and axially positioned by screws as in the tool body a. In this construction the blade will extend a set distance from the depth limiting shoulder 102 and conical tip 100 of the tool body. In operation of this tool assembly the cutting blade will contact the workpiece before the depth of cut limiting means in a manner similar to that of tool assembly T2. Otherwise operation will be the same as that described in connection with tool assembly T3.

FIGS. 12 and 13 show a tool assembly generally designated by the symbol T4, which may be used for external chamfering. Parts corresponding to those of tool assemblies Tl-T3 are identically numbered. A tool body 200 is cylindrical and has a generally conical bore 125 in one end to receive a workpiece W to be chamfered. Another cylindrical bore 56c in the tool body slidably receives the cylindrical holder 60 for securing a cutting blade 700. The flange 45 of driver 44 bears against the end face of the blade holder 60 which is held retracted in bore 56c by the expanded springs 62. An inclined cutting edge 79c on blade 700 is normally disposed in registration with an edge 126 of a slot 26c into which the blade is sheathed. The screws 74 which hold the blade 700 may be reached via holes 800 in the tool body 20c. Further holes 130 in a cylindrical cap 300 register with the holes 80c. A cutout 132 is formed in the cylindrical cap 300 and edge thereof registers with the edge of cutaway or relieved portion 134 of the tool body 20c. The pair of screws 36 pass through loosely fitting holes 49 in flange 45 and are seated in threaded holes 131 in the tool body 200 to hold the cap c thereto.

In operation of tool assembly T4, the workpiece W is inserted in the conical bore 125 of the tool body 200 which rotates with respect to the workpiece. When the driver member 44 is axially advanced (the maximum depth of cut being determined by the spacing between end cap 30c and collar 51), the blade 700 is advanced and oblique cutting edge 79c engages the end of the workpiece to perform the chamfering or beveling operation. Slight retraction of the driver member 44 will permit the blade 700 to be retracted into its sheathing slot 260 while the tool body and workpiece continue relative rotation.

It is possible to reconstruct the tool assembly T4 to secure the blade 70c in fixed rather than movable position in a manner similar to that described in connection with the tool assembly T2. In such a construction the cutting edge of the blade will engage the workpiece W before the tool body. Otherwise operation will be the same as described above.

FIGS. 14 and 15 show a tool assembly generally designated by reference symbol T5 which may be used for boring the inside of a hole, facing end forming and counterboring- Parts corresponding to those of tool assembly T1 are identically numbered. A tool body 2011 is cylindrical and has a cylindrical bore or recess 56d which slidably receives cylindrical holder 60 for securing a cutting blade 70d. The tool body has a cylindrical extension 150 which engages in a hole H in workpiece W indicated by dotted lines in FIG. 14, and which serves as a guide piece. Slot 26d slidably receives the blade 70d. The cap 30 fits on the cylindrical tool body and is held by screws 36 which pass through holes 49 in flange 45. The shaft 46 of tool driver 44 extends through the central hole and bore in the cap circular face 32. The blade 70d is held in the slot 72 of the blade holder 60 by a pair of screws 74. The springs 62 as in the aforedescribed embodiments, retract the blade and blade holder. The edge 79d of the cutting blade 70d is retracted in the slot 26d. The cylindrical bore is cut away at a flat face 24d to clear cuttings made by the cutting edge 79d of the blade. The collar 51 is held by the screw 52 and determines the distance the blade will be advanced when pressure is applied to driving shaft 46. A pair of screws 84d in the tool body 20d which open into the slot 26d adjustably determine the radial position of the blade 70d. Access holes d expose the screws 74 for removing the cutting blade without disassembling the parts of the assembly.

In operation of the tool assembly, the guide piece will be engaged in hole H of workpiece W'QA shoulder 152 of the tool body 20d will bear on the workpiece. When there is relative rotational motion between the tool assembly and the workpiece and the tool driver is under axial pressure, the springs 62 will be compressed and the cutting blade will be extended to cut the inside of hole H. The blade will be retracted when pressure on the tool driver is relieved, although relative motion between the tool assembly and the workpiece continues. The tool assembly T5 can be reconstructed in a manner mentioned in connection with tool assemblies T2, T3, and T4 to mount blade 70d in a fixed position on tool body 20d. In this arrangement, the cutting blade will contact the workpiece before the shoulder 152 of the tool body. Otherwise operation of the tool assembly T5 will be the same as described above.

FIGS. 16 and 17 show a tool assembly generally designated by symbol T6 which may be used to turn or cut the outside diameter of a workpiece W The tool assembly T6 includes a guidance means and depth of cut control means. The guidance means for the workpiece is adjustable so that an unlimited number of workpiece diameters may be accommodated. In tool assembly T6, a tool body 20c is comprised of a generally hollow cylindrical member formed with an internal radial, annular shoulder 162 and a lateral cutout portion 170. Chips are removed through the slot or cutout portion 170. A cylindrical depth of cut guide fits into an axial bore 174 of the tool body 20e, and seats on the shoulder 162. This shoulder has tapped holes to engage ends of a pair of screws 36e which extend through holes 38 in cap 30, holes 40 in flange 45, holes 164 in a blade holder 60c and holes 161 in the depth of cut guide 160. A cutting blade 70e has a cutting edge 79e at its end. The blade fits into a slot 72 which engages screws 74e in tapped holes 75e of the blade holder. The depth of cut guide 160 has blind holes 175, which are adapted to receive coil springs 62e. These springs extend outwardly of the depth of cut guide and bear against the blade holder 60a. A slot in the depth of cut guide 160 accommodates the blade 70e and a cylindrical axial bore 182 accommodates the turned or cut section S of workpiece The blade 70e is held retracted by springs 62e. Screws 84 in holes 82e in the tool body determined the radial position of blade 70e. Holes 80e provide access to screws 74e for removing and replacing the blade. When the springs 62c are expanded the blade holder contacts the flange 45 of the driver 44. When the springs are contracted by pressing the tool driver 44 axially forward, the cutting edge 79c of the blade is projected out of the sheathing slot 180 through the guide 160 to cut the workpiece. The collar 51 is adjustable and locked by the screw 52 to set the distance between the collar 51 and the end cap 30 which distance determines the maximum depth of cut and thus the feed as in the previous axially movable embodiments.

When the workpiece is inserted in a bore 179 of the tool body 202 and is engaged by an end face 185 of the workpiece guide 160, and there is relative motion between the workpiece and tool body, a forward axial movement of the tool driver 44 extends blade 70e to cut the workpiece. When the pressure on the tool driver 44 is relaxed, the blade 70e is retracted into sheathing slot 180, while relative rotation between the tool assembly and workpiece may continue. The guide 160 is a replaceable part of the tool body and thus guides of different axial lengths, (i.e., distance between end face 185 and face v'7 p v 186 of the guide 160) may be provided for extending the blade different distances. Bore 182 in the guide 160 receives and guides cut section S of the workpiece.

The tool assembly T6 may be reconstructed by securing the blade 70a to the tool guide 160 which may be integral with the tool body. The blade will project a fixed sitance into the bore 179 and contact the workpiece first before the depth of cut guide 160. Otherwise operation will be the same as described above in connection with Tool Assembly T6.

in all forms of the invention described, where a cutting with cylindrical sections for holding said tool body and said workpiece in a mutually engaged relatively rotating position.

blade is movably mounted, the blade is retracted when pressure is relieved on the tool driver. When pressure is applied thereto, the blade moves forwardly from a sheathing slot in the tool body to contact and cut the work. Where the tool assembly has a fixed blade, the blade contacts the workpiece first. However, the workpiece and tool assembly are held in a mutually engaging relationship which insures accurate, precision cutting while they rotate with respect to each other.

lt should also be understood that the foregoing relates to only preferred embodiments of the invention, and that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purposes of the disclosure, which do not constitute departures from the spirit and scope of the invention.

The invention claimed is:

l. A rotating tool assembly for machining a workpiece,

comprising,

a generally cylindrical tool body having an axial extending slot;

a cutting blade removably secured in said slot;

means for limiting axial depth of cut per revolution of said tool assembly by said blade; and

guide means for holding said tool body and said workpiece in mutually engaged relatively rotatably position and for guiding said blade in cutting said workpiece.

2. A tool assembly as defined in claim 1, further comprising screws means in said tool body for adjustably positioning'said blade in said slot radially of said tool body.

3. A tool assembly as defined in claim 1, further comprising screw means in said tool body for adjustably positioning said blade in said slot longitudinally of said tool body.

4. A. tool assembly as defined in claim 1, wherein said guide means comprise a stepped, generally conical configuration,

5. A tool assembly as defined in claim 1, further comprising screw means in said tool body for adjustably positioning said blade in said slot radially of said tool body; and

further screw means in said tool body for adjustably positioning said blade in said slot, longitudinally of said tool body.

6. A tool assembly as defined in claim 1 further comprising a tool driver operatively connected to said tool body for maintaining relative rotation betweensaid tool body and said workpiece whereby said workpiece may be cut by said blade.

7. A tool assembly as defined in claim 6, further comprising a blade holder axially slidable in said tool body; 7

spring means in said tool body normally holding said blade axially retracted in said slot; and

means supporting said tool driver for axial movement with respect to said tool body, said blade holder being disposed for longitudinal movement in said slot by said tool driver against tension in said spring means to extend beyond said slot for cutting said workpiece. 8. A tool assembly as defined in claim 7, further comprising means adjustably engageable with said tool driver and positionable with respect to said tool body so as to determine the extent of axial movement of said tool driver, blade holder and blade with respect to said tool body.

9. A tool assembly as defined in claim 8, wherein said guide means comprise a stepped, generally conical configuration, with cylindrical sections for holding said tool body and said workpiece in a mutually erggaged relatively rotatingposi tion.

10. A tool assembly as e med in claim 7 wherein said tool driver comprises a cylindrical shaft extending axially of said body, and said means for limiting axial depth of cut,*includes a collar adjustably engageable on said shaft and positionable with respect to said tool body so as to determine the extent of axial movement of said tool driver, blade holder and blade with respect to said tool body.

11. A tool assembly as defined in claim 7, further comprising screw means in said tool body for adjustably positioning said blade in said slot radially of said tool body; and

further screw means in said tool body for adjustably positioning said blade in said slot longitudinally of said tool body. 

1. A rotating tool assembly for machining a workpiece, comprising, a generally cylindrical tool body having an axial extending slot; a cutting blade removably secured in said slot; means for limiting axial depth of cut per revolution of said tool assembly by said blade; and guide means for holding said tool body and said workpiece in mutually engaged relatively rotatably position and for guiding said blade in cutting said workpiece.
 2. A tool assembly as defined in claim 1, further comprising screws means in said tool body for adjustably positioning said blade in said slot radially of said tool body.
 3. A tool assembly as defined in claim 1, further comprising screw means in said tool body for adjustably positioning said blade in said slot longitudinally of said tool body.
 4. A tool assembly as defined in claim 1, wherein said guide means comprise a stepped, generally conical configuration, with cylindrical sections for holding said tool body and said workpiece in a mutually engaged relatively rotating position.
 5. A tool assembly as defined in claim 1, further comprising screw means in said tool body for adjustably positioning said blade in said slot radially of said tool body; and further screw means in said tool body for adjustably positioning said blade in said slot longitudinally of said tool body.
 6. A tool assembly as defined in claim 1 further comprising a tool driver operatively connected to said tool body for maintaining relative rotation between said tool body and said workpiece whereby said workpiece may be cut by said blade.
 7. A tool assembly as defined in claim 6, further comprising a blade holder axially slidable in said tool body; spring means in said tool body normally holding said blade axially retracted in said slot; and means supporting said tool driver for axial movement with respect to said tool body, said blade holder being disposed for longitudinal movement in said slot by said tool driver against tension in said spring means to extend beyond said slot for cutting said workpiece.
 8. A tool assembly as defined in claim 7, further comprising means adjustably engageable with said tool driver and positionable with respect to said tool body so as to determine the extent of axial movement of said tool driver, blade holder and blade with respect to said tool body.
 9. A tool assembly as defined in claim 8, wherein said guide means comprise a stepped, generally conical configuration, with cylindrical sections for holding said tool body and said workpiece in a mutually engaged relatively rotating position.
 10. A tool assembly as defined in claim 7 wherein said tool driver comprises a cylindrical shaft extending axially of said body, and said means for limiting axial depth of cut, includes a collar adjustably engageable on said shaft and positionable with respect to said tool body so As to determine the extent of axial movement of said tool driver, blade holder and blade with respect to said tool body.
 11. A tool assembly as defined in claim 7, further comprising screw means in said tool body for adjustably positioning said blade in said slot radially of said tool body; and further screw means in said tool body for adjustably positioning said blade in said slot longitudinally of said tool body. 